This invention relates to liquid dispensing apparatus and, more particularly, it concerns an improved visual flow indicating system for a fuel dispenser.
Visual fluid flow indicators are well known in the fuel dispenser art and conventionally employ a metallic base having a fluid inlet and a fluid outlet which feed fluid thru a chamber created by the attachment of a dome-shaped transparent cover to the base. A number of movable indicating elements, such as, brightly colored balls are enclosed within the chamber so that when fluid flows through the indicator, the movable flow indicating elements circulate about the chamber and provide a visual indication that flow is occurring and, thus, fuel is being dispensed. The transparent cover also allows for a visual inspection of the fluid being dispensed and an opportunity to ascertain whether or not air or gas is being dispensed along with the liquid.
Early fuel pump flow indicator designs, such as described, for example, in U.S. Pat. No. 1,730,118 issued to R. W. Cobb on Oct. 1, 1929, incorporated relatively large flow indicators which accommodated the full fluid flow of the liquid being dispensed. Such indicators were placed in the fuel dispensing conduit between the fuel pump and the flexible dispensing hose. Since all of the liquid being dispensed had to flow through the flow indicator, any resistance to flow created by the flow indicator tended to reduce the flow rate of the liquid being dispensed.
In an effort to reduce the size, bulk, and expense of the above-mentioned large-sized flow indicators, fractional or partial flow indicator systems were developed. In such a fractional flow indicator system, only a portion of the fluid flowing through a dispenser conduit is diverted to a relatively small-sized visual flow indicator. One example of such a fractional flow indicator system is described in U.S. Pat. No. 2,678,624 issued to A. L. Grise et al on May 18, 1954.
Another example of a conventional fractional flow indicating system is shown in FIGS. 1-3 of the drawings and generally designated by the reference numeral 10. The flow indicating system 10 includes a fractional flow diverting section generally designated 12 (FIGS. 1 and 3) which provides a fractional fluid flow to a flow indicator 14 (FIGS. 1 and 2) when fluid is being dispensed. The fractional flow diverting section 12 includes a fractional flow output 16 in a flow conduit 18 of a meter support and diaphragm valve 20, a restrictor valve 22 (shown in a closed position) located between the flow conduit 18 and a curved elbow 24 which leads to a fluid conduit or pipe 26, and a fractional flow return 28 in the curved elbow 24.
Typically, the fractional flow output 16 and return 28 are each 1/8N.P.T..times.1/4O.D.T. brass elbow fittings which are secured within respective threaded openings in the conduit 18 and the curved elbow 24. Lengths 30 and 32 of 1/4 inch copper tubing operatively connect the fractional flow output 16 and return 28 to the flow indicator 14.
When the fluid pressure in the conduit 18 exceeds the back pressure provided by the spring in the check valve 22, the valve 22 opens and allows fluid to flow from the conduit 18 to the curved elbow 24, pipe 26 and eventually through a flexible hose and dispensing nozzle (not shown) in a conventional manner. As fluid flows through the conduits 18 and 26, the check valve 22 creates a pressure drop between the fluid in the upstream conduit 18 and the downstream conduit 26. This pressure differential created by the restrictor valve 22 is sufficient to induce fluid flow through the fractional output 16, up through the tubing 30, through the flow indicator 14, down through the tubing 32 and back through the fractional flow return 28 into the curved elbow 24.
Although the restrictor valve 22 is effective at providing a sufficient pressure differential to induce flow through the flow indicator 14, there are several drawbacks associated with such a restrictor valve. Since substantially all of the fluid being dispensed must pass through the restrictor valve 22, the valve tends to reduce the fluid flow rate and pressure. One method of compensating for this reduction in flow rate and pressure is by using more expensive fuel pumps and motors capable of producing greater fluid flow rates and pressures. Also, the restrictor valve 22 includes one or more gaskets 34 and moving parts which are subject to wear. Furthermore, assembly of the flow diverting section 12 of flow indicating system 10 requires that respective threaded openings be constructed in the conduit 18 and the curved elbow 24 to accommodate the output 16 and the return 28.
With reference again to FIGS. 1 and 2 of the drawings, the flow indicator 14 includes a metallic base 36 having a threaded fluid inlet 38 and a threaded fluid outlet 40. The inlet 38 receives a small-sized elbow fitting 42 which in turn receives the upper end of the tubing 30. The outlet 40 receives a straight fitting 44 within which the upper end of the tubing 32 is received.
The flow indicator 14 further includes a dome-shaped glass cover 46 having a circular base including a circumferentially extending flange 48 which facilitates attachment of the cover 46 to the indicator base 36 by a clamp ring 50. The clamp ring 50 is fastened to the indicator base 36 by four counter sunk, flat head machine screws (not shown). An o-ring 52 is provided between the clamp ring 50 and the glass flange 48 to ensure that the flange 48 is not damaged. Another o-ring 54 is partially received within an annular recess 56 in the indicator base 36 opposite the cover flange 48 in order to provide a fluid tight seal between the base 36 and the glass cover 46.
A fluid chamber 58 defined in large part by the inner surface of the glass dome 46 houses a pair of movable flow indicating elements or balls 60. A multi-part pedestal 62 made up of a round head machine screw 64, a washer 66, and a lock nut 68 is disposed within the chamber 58 with the shaft of the machine screw 64 being received within a threaded bore 70 in the base 36. The washer 66 of the pedestal 62 keeps the balls 60 from blocking the fluid outlet 40 and also serves to protect an inlet nozzle 72.
The nozzle 72 is partially received within an angled port 74 which operatively connects the inlet 38 with the fluid chamber 58. The angled port 74 and the nozzle 72 must both be machined to exacting tolerances so that a fluid tight seal is formed between the inner surface of the angled port 74 and the outer surface of the nozzle 72. The nozzle 72 includes a small jet or opening 76 which accelerates the fluid passing through the nozzle 72 and directs the fluid in a manner producing a positive circulating motion of the fluid and the balls 60 in the chamber 58.
As shown most clearly in FIG. 1 of the drawings, the flow indicator 14 is attached to a side wall 78 of a fuel dispenser 80 by an angled bracket member 82. The glass dome 46 and a portion of the clamp ring 50 protrude from a circular opening in an upper side sheath 84 to provide a visual indication of fluid flow when fuel is being dispensed from the dispenser 80.
Even though the above-described flow indicator 14 provides an effective visual indication of fluid flow through the fluid conduits 18 and 26, construction and assembly of such an indicator is complicated and expensive in that the indicator is made up of a number of parts and, as such, requires a number of assembly steps and because the nozzle 72 and angled port 74 must be machined to exacting tolerances.
In light of the foregoing, there is a need for an improved flow indicator system, fractional flow diverting component and/or flow indicator.